How dim is Florida's energy outlook?

Each lugs 20 million pounds of energy-rich ore from an Appalachian mine five states away to a ravenous electric plant east of the city.

Even at about $750,000 a load, coal is a bargain when compared to other sources of energy. That's why it reigns as the favorite fuel of the Orlando Utilities Commission, which has kept its rates among the lowest in Florida.

Now, however, utilities everywhere fear coal is losing its luster. Momentum is growing for national limits and penalties on emissions of greenhouse gases, air pollution blamed for global warming.

Coal-powered electricity plants are among the biggest offenders, meaning the price of burning coal could shoot far above today's already significant cost. OUC, for example, spends $175 million a year on the fuel.

The prospect of soaring coal bills has sent utilities on a quest to harness other fuels and technologies that don't spew as much greenhouse gas.

They are ready and willing to spend lots of cash, which has brought to life a bazaar of merchants, coal miners, oil drillers, biofuel farmers, friends of nuclear, politicians, lobbyists, scientists and environmentalists vying feverishly over the future of energy.

But there are many unknowns, especially when it comes to the potential speed and severity of federal limits on greenhouse gases. Also looming are government mandates that utilities embrace solar, wind and other renewable forms of energy.

Coal grew to dominate the electricity business in the 1960s and has clung to its status thanks partly to setbacks for competing methods of making electricity.

Following petroleum shortages in the 1970s, Congress barred utilities from building plants fueled by natural gas. The law stayed on the books until the mid-1980s.

National support for nuclear plants took a dive after the Three Mile Island partial meltdown 30 years ago this month.

Today, half of the nation's electricity comes from coal-powered plants. Still, even with the federal government deliberating caps on climate-warming carbon dioxide, coal has begun to slip from its pedestal.

In 2007, Gov. Charlie Crist announced opposition to coal because of its part in global warming. Within months, a half-dozen proposed plants in the state were shelved.

OUC was hoping to build one of those generators. It would have ranked among the cleanest in the nation as far as mercury, acid rain and smog pollutants. But neither OUC nor any other utility knows for certain how to build a power plant that captures and permanently stores carbon dioxide.

So sudden was the shift away from coal in Florida that OUC canceled the plant just two months after its groundbreaking.

Plans for nearly 100 new coal plants across the nation have collapsed in the past few years as environmental groups fought proposals in state legislative hearings, local zoning hearings, air-quality reviews and regulatory proceedings.

"Coal is by far the filthiest fuel," said Bruce Nilles, director of the Sierra Club's Move Beyond Coal campaign.

With penalties on greenhouse gases expected within a few years, OUC ranks among utilities that have the most to worry about. The city electricity provider, owning a pair of large and relatively young coal-powered plants, relies on the fuel to make more than 70 percent of its electricity.

By comparison, the far bigger Florida Power & Light Co. makes about 6 percent of its electricity with coal.

FPL is pushing for limits on greenhouse gases. OUC is not.

"It would be a very big impact to our customers if we had to reduce output of our power plants," OUC Chief Executive Officer Ken Ksionek said.

Gas gamble

Not certain what the future holds, utilities have stampeded to natural gas, a fuel that releases less carbon dioxide than coal.

Florida already relies heavily -- too heavily, utility experts say -- on the fossil fuel. That's because the state's explosive growth during the past 20 years came when utilities learned to favor natural-gas power plants as cheaper, faster to build and able to meet increasingly tough laws on air pollution.

Today, natural gas costs more than coal and is prone to big swings in price. It also arrives in Florida via just two pipeline systems, making state officials nervous about a disaster or accident that could shut down the flow.

Utilities aren't deterred.

Last year, FPL president Armando Olivera traveled to Brevard County to announce a $1 billion plan to demolish an aging plant in Port St. John and replace it with a far larger one. It would run on natural gas. Crist sent a note of congratulations, while environmentalists praised FPL's decision to go with natural gas as a bridge to the future of energy.

FPL's president said it was more than that.

"I think we are going to rely on natural gas for a long, long time," Olivera said.

Nuclear power

For now, many utilities say their top energy choice is to go with new nuclear power plants.